So far, we have concentrated on describing consonant sounds in terms of where they are articulated. We can also describe the same sounds in terms of how they are articulated. Such a description is necessary if we want to be able to differentiate between some sounds which we have placed in the same category. For example, we can say that [t] and [s] are both voiceless alveolar sounds. How do they differ? They differ in their manner of articulation, that is, in the way they are pronounced. The [t] sound is one of a set of sounds called stops and the [s] sound is one of a set called fricatives.
Stops (plosives)
Of the sounds we have already mentioned, the set [p], [b], [t], [d], [k], [g] are all produced by some form of ‘stopping’ of the airstream (very briefly) then letting it go abruptly. This type of consonant sound, resulting from a blocking or Shopping effect on the airstream, is called a stop (or a ‘plosive’). A full description of the [t] sound at the beginning of a word like ten is as a voiceless alveolar stop. In some discussions, only the manner of articulation is mentioned, as when it is said that the word bed, for example, begins and ends with voiced stops.
Fricatives
The manner of articulation used in producing the set of sounds [f], [v], [θ], [d], [s], [z], [ʃ], [_] involves almost blocking the airstream and having the air push through the very narrow opening. As the air is pushed through, a type of friction is produced and the resulting sounds are called fricatives. If you put your open hand in front of your mouth when making these sounds, [f] and [s] in particular, you should be able to feel the stream of air being pushed out. The usual pronunciation of the word fish begins and ends with the voiceless fricatives [f] and [ʃ]. The word those begins and ends with the voiced fricatives [d] and [z].
Affricates
If you combine a brief stopping of the airstream with an obstructed release which causes some friction, you will be able to produce the sounds [tʃ] and [d_]. These are called affricates and occur at the beginning of the words cheap and jeep. In the first of these, there is a voiceless affricate [tʃ], and in the second, a voiced affricate [d_].
Nasals
Most sounds are produced orally, with the velum raised, preventing airflow from entering the nasal cavity. However, when the velum is lowered and the airstream is allowed to flow out through the nose to produce [m], [n], and [ŋ], the sounds are described as nasals. These three sounds are all voiced. The words morning, knitting and name begin and end with nasals.
Liquids
The initial sounds in led and red are described as liquids. They are both voiced. The [l] sound is called a lateral liquid and is formed by letting the airstream flow around the sides of the tongue as the tip of the tongue makes contact with the middle of the alveolar ridge. The [r] sound at the beginning of red is formed with the tongue tip raised and curled back near the alveolar ridge.
Glides
The sounds [w] and [j] are described as glides. They are both voiced and occur at the beginning of we, wet, you and yes. These sounds are typically produced with the tongue in motion (or ‘gliding’) to or from the position of a vowel and are sometimes called semi-vowels or approximants.
The sound [h], as in Hi or hello, is voiceless and can be classified as a glide because of the way it combines with other sounds. In some descriptions, it is treated as a fricative.
The glottal stop and the flap
There are two common terms used to describe ways of pronouncing consonants.
The glottal stop, represented by the symbol [ʔ], occurs when the space between the vocal cords (the glottis) is closed completely (very briefly), then released. Try saying the expression Oh oh. Between the first Oh and the second oh, we typically produce a glottal stop. Some people do it in the middle of Uh-uh (meaning ‘no’), and others put one in place of t when they pronounce Batman quickly. You can also produce a glottal stop if you try to say the words butter or bottle without pronouncing the -tt- part in the middle. This sound is considered to be characteristic of Cockney (London
If, however, you are an American English speaker who pronounces the word butter in a way that is close to ‘budder’, then you are making a flap. It is represented by [D] or sometimes [ɾ]. This sound is produced by the tongue tip tapping the alveolar ridge briefly. Many American English speakers have a tendency to ‘flap’ the [t] and [d] consonants between vowels so that, in casual speech, the pairs latter and ladder, writer and rider, metal and medal do not have distinct middle consonants. They all have flaps. The student who was told about the importance of Plato in class and wrote it in his notes as play-dough was clearly a victim of a misinterpreted flap.